1. Field of the Invention
The present invention relates to a method and apparatus for controlling the air-fuel ratio in an internal combustion engine in which a fuel increment for warming up the engine is carried out in accordance with the temperature of the engine coolant.
2. Description of the Related Art
In general, fuel enrichment for engine warm-up is carried out in accordance with the temperature of the engine coolant. When an engine is started at an extremely low temperature, the temperature of the intake air does not rise as rapidly as the temperature of the engine coolant. Accordingly, the controlled air-fuel ratio tends to be on the lean side, inviting poor drivability, backfires, and the like.